摘要Targeted covalent inhibitors,primarily targeting cysteine residues,have attracted great attention as potential drug candidates due to good potency and prolonged duration of action.However,their dis-covery is challenging.In this research,a database-assisted liquid chromatography-tandem mass spec-trometry(LC-MS/MS)strategy was developed to quickly discover potential cysteine-targeting compounds.First,compounds with potential reactive groups were selected and incubated with N-acetyl-cysteine in microsomes.And the precursor ions of possible cysteine-adducts were predicted based on covalent binding mechanisms to establish in-house database.Second,substrate-independent product ions produced from N-acetyl-cysteine moiety were selected.Third,multiple reaction monitoring scan was conducted to achieve sensitive screening for cysteine-targeting compounds.This strategy showed broad applicability,and covalent compounds with diverse structures were screened out,offering structural resources for covalent inhibitors development.Moreover,the screened compounds,norket-amine and hydroxynorketamine,could modify synaptic transmission-related proteins in vivo,indicating their potential as covalent inhibitors.This experimental-based screening strategy provides a quick and reliable guidance for the design and discovery of covalent inhibitors.